Add unsupported block title translation test (#33340)

* Add unsupported block title translation test

* Update unsupported block placeholder test

- Instead of checking if the `_x` translation function was called, we now instead mock the translations and verify that the translated string appears in the UI.
- Add a test to verify translations in the unsupported block bottom sheet title.

* Tweak element query for clarity

packages/block-library/src/missing/test/edit-integration.native.js

@@ -0,0 +1,84 @@
+/**
+ * External dependencies
+ */
+import { initializeEditor, fireEvent, waitFor, within } from 'test/helpers';
+
+/**
+ * WordPress dependencies
+ */
+import { getBlockTypes, unregisterBlockType } from '@wordpress/blocks';
+import { setLocaleData } from '@wordpress/i18n';
+
+/**
+ * Internal dependencies
+ */
+import { registerCoreBlocks } from '../..';
+
+beforeAll( () => {
+	// Mock translations
+	setLocaleData( {
+		'block title\u0004Table': [ 'Tabla' ],
+		"'%s' is not fully-supported": [ '«%s» no es totalmente compatible' ],
+	} );
+
+	// Register all core blocks
+	registerCoreBlocks();
+} );
+
+afterAll( () => {
+	// Clean up translations
+	setLocaleData( {} );
+
+	// Clean up registered blocks
+	getBlockTypes().forEach( ( block ) => {
+		unregisterBlockType( block.name );
+	} );
+} );
+
+describe( 'Unsupported block', () => {
+	it( 'requests translated block title in block placeholder', async () => {
+		const initialHtml = `<!-- wp:table -->
+			 <figure class="wp-block-table"><table><tbody><tr><td>1</td><td>2</td></tr><tr><td>3</td><td>4</td></tr></tbody></table></figure>
+			 <!-- /wp:table -->`;
+		const { getByA11yLabel } = await initializeEditor( {
+			initialHtml,
+		} );
+
+		const missingBlock = await waitFor( () =>
+			getByA11yLabel( /Unsupported Block\. Row 1/ )
+		);
+
+		const translatedTableTitle = within( missingBlock ).getByText(
+			'Tabla'
+		);
+
+		expect( translatedTableTitle ).toBeDefined();
+	} );
+
+	it( 'requests translated block title in bottom sheet', async () => {
+		const initialHtml = `<!-- wp:table -->
+		 <figure class="wp-block-table"><table><tbody><tr><td>1</td><td>2</td></tr><tr><td>3</td><td>4</td></tr></tbody></table></figure>
+		 <!-- /wp:table -->`;
+		const { getByA11yLabel, getByText } = await initializeEditor( {
+			initialHtml,
+		} );
+
+		const missingBlock = await waitFor( () =>
+			getByA11yLabel( /Unsupported Block\. Row 1/ )
+		);
+
+		fireEvent.press( missingBlock );
+
+		const helpButton = await waitFor( () =>
+			getByA11yLabel( 'Help button' )
+		);
+
+		fireEvent.press( helpButton );
+
+		const bottomSheetTitle = await waitFor( () =>
+			getByText( '«Tabla» no es totalmente compatible' )
+		);
+
+		expect( bottomSheetTitle ).toBeDefined();
+	} );
+} );